An investigation into formaldehyde levels within unoccupied newly built residential dwellings in Auckland

Abstract

Newly built dwellings pose a risk that their occupants may develop adverse health effects from exposure to the indoor air pollutant formaldehyde released by building materials. Despite the known health risks associated with this pollutant, there has been minimal examination into its concentrations produced in New Zealand residential dwellings (NZGBC, 2013). The aim of this study was to measure formaldehyde concentrations in a number of newly built residential dwellings in the Auckland region that were unoccupied and unfurnished. Levels were recorded with handheld portable electronic monitors and passive samplers. Measurements were restricted to kitchens and bedrooms, as these are typically the focal areas in which occupants congregate for extended periods. Average formaldehyde levels for the 27 sampled dwellings were recorded in the range 0ppm to 0.37ppm, which are all below the New Zealand workplace time-weight average exposure standard of 0.5ppm. In some cases, the levels exceeded standards and guidelines set by other countries. However, formaldehyde levels did exceed the current and proposed new occupational limits for New Zealand when time weighted exposure averages were extended for a full week, suggesting low-level exposure over extended periods may have the potential to cause adverse health effects. Regression analysis, and a Pearson Correlation, identified an overall positive correlation between formaldehyde concentration and temperature, and an overall negative correlation between formaldehyde concentration and relative humidity, findings that concur with several overseas studies. The limited number of dwellings sampled did not produce convincing evidence as to the source of formaldehyde, but those dwellings that had wooden laminate flooring did display higher readings than other dwellings. Measurements inside cupboards also produced higher readings, suggesting that the medium density fibreboard from which they were constructed was a formaldehyde source. The degree to which a dwelling was not subject to indoor/outdoor air exchange also positively affected formaldehyde levels, and the decay rate of levels. It was also noted that chemicals used for cleaning positively impacted on formaldehyde levels but were quick to disperse. Limitations of the study are discussed together with suggestions for improvements in its design.